ECMA-339

This Standard specifies signalling interworking between “QSIG” and the Session Initiation Protocol (SIP) in support of basic services within a corporate telecommunication network (CN).

“QSIG” is a signalling protocol that operates between Private Integrated Services eXchanges (PINX) within a Private Integrated Services Network (PISN). A PISN provides circuit-switched basic services and supplementary services to its users. QSIG is specified in other Ecma Standards, in particular ECMA-143 (call control in support of basic services), ECMA-165 (generic functional protocol for the support of supplementary services) and a number of Standards specifying individual supplementary services.

SIP is an application layer protocol for establishing, terminating and modifying multimedia sessions. It is typically carried over the Internet Protocol (IP) (IETF RFC 791 and IETF RFC 2460). Telephone calls are considered as a type of multimedia session where just audio is exchanged. SIP is defined in IETF RFC 3261.

This Standard specifies signalling interworking for basic services that provide a bi-directional transfer capability for speech, DTMF, facsimile and modem media between a PISN employing QSIG and a corporate IP network employing SIP. Call-related and call-independent signalling in support of supplementary services is outside the scope of this Standard, but support for certain supplementary services (e.g., call transfer, call diversion) could be the subject of future work.

Interworking between QSIG and SIP permits a call originating at a user of a PISN to terminate at a user of a corporate IP network, or a call originating at a user of a corporate IP network to terminate at a user of a PISN.

Interworking between a PISN employing QSIG and a public IP network employing SIP is outside the scope of this Standard. However, the functionality specified in this Standard is in principle applicable to such a scenario when deployed in conjunction with other relevant functionality (e.g., number translation, security functions, etc.).

This standard is applicable to any interworking unit that can act as a gateway between a PISN employing QSIG and a corporate IP network employing SIP.